Field of the Invention
Embodiments of the invention relate to a quantum rod (QR), and more particularly, to a QR having high quantum efficiency and high off-property and a QR film and a QR display device including the same.
Discussion of the Related Art
Recently, applications of the QR to display devices and lightening devices have been researched.
Since the QR has high emitting efficiency and excellent reproducibility, the QR can be applied to various uses.
Since extinction coefficient and quantum yield of the QR is very large in comparison to general dyes, the QR emits strong fluorescent light. In addition, by controlling a diameter of the QR, a wavelength of light emitted from the QR can be controlled.
The QR emits linearly-polarized light. Namely, the light from the QR has a linearly-polarized property along a length direction of the QR. In addition, the QR has an optical property that is capable of controlling emission by an electric field applied from the outside. This may be referred to as stark effect. By using these properties, the optical efficiency of the display device and/or the lightening device can be improved.
FIGS. 1A and 1B are schematic view illustrating a driving principle of the related art QR.
As shown in FIGS. 1A and 1B, a QR 20 includes a core 22, which is formed a nano-size semiconductor material, and a shell 24 covering the core 22. For example, the core 22 may be formed of the XII-XVI group semiconductor material, the XIII-XV group semiconductor material, the XI-XIII-XVI group semiconductor material or the XIV-XVI group semiconductor material, and the shell 24 may be formed of XII-XVI group semiconductor material such as ZnS.
As shown in FIG. 1A, the QRs 20 are arranged on a base 10. Without voltage, the electron “e−” and the hole “h+” are combined in the core 22 such that the QR 20 emits the light. (emission ON)
On the other hand, as shown in FIG. 1B, with voltage, i.e., with an electric field “E”, the electron “e−” and the hole “h+” are separated such that the emission of the QR 20 is finished. (emission OFF)
Namely, the QR 20 is driven by the electric field, and the QR 20 is used for the display device and/or the lightening device.
In the related art QR 20, the quantum efficiency and the off property are in the trade-off relation.
Namely, in a QR display device (or a QR lightening device) including high quantum efficiency (or emission efficiency) QRs 20, the off property of the QR is low such that the contrast ratio is decreased. On the other hand, in a QR display device (or a QR lightening device) including high off property QRs 20, the quantum efficiency of the QR is low such that the brightness is decreased.